In the book Cardiothoracic Surgery by J. Chikwe et al. (Oxford, 2nd ed. 2013) there is a diagram of cardiopulmonary bypass (CPB) that provides a still, bloodless heart, while circulation to the rest of the body is maintained. In CPB, one of the safety components used in every system is a one-way valve in the left ventricular vent. Different designs for this one-way check valve are exemplified by the following prior art.
In U.S. Pat. No. 5,707,356 G. Paul discloses an overpressure check valve assembly for use during heart surgery. The assembly comprises an elongated tubular body portion having an inlet end, and an outlet end and a unidirectional valve disposed therebetween. A relief valve portion is joined to and in flow communication with the tubular portion. The relief valve portion includes a first relief valve configured to open if the pressure within the overpressure safety valve diminishes below a predetermined level, and a second relief valve configured to open if the pressure adjacent the outlet end exceeds a predetermined level. The first and second relief valves are disposed in a side by side configuration in a common conduit.
In U.S. Pat. No. 4,758,224 G. Siposs discloses a check valve that is positioned in the left ventricle drain line which permits flow only away from the heart. A vent valve is located downstream of the check valve to prevent buildup of pressure and includes an inwardly directed umbrella valve to limit left ventricle drain line vacuum intensity applied to the heart.
In U.S. Pat. No. 4,671,786 J. Krug discloses a safety check valve for heart surgery to prevent overpressure wherein the valve has an elongated tubular body portion with an inlet end, and an outlet end and a unidirectional valve disposed therebetween. A relief valve portion is joined to and in flow communication with the tubular portion. The relief valve portion includes a first relief valve configured to open if the pressure within the overpressure safety valve diminishes below a predetermined level, and a second relief valve configured to open if the pressure adjacent the outlet end exceeds a predetermined level.
While all of the prior art overpressure check valves are useful, a problem still exists in CPB where there is simultaneously some pressure from the heart or the pump circuit on the inlet side and some suction of blood or fluid by a pump on the outlet side. A pressure imbalance can occur due to kinks in conduits or improper connections of CPB lines on setup or line blockages. An object of the invention was to provide a CPB check valve that prevents one side from overpowering the other, particularly if a conduit kink, improper connection or line blockage should occur.